RECYCLE AND BENEFICIAL REUSE GROUP

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The Reuse/Recycling Program Group strives to harness the environmental benefits of reusing and recycling of industrial or other recycled materials. The Team host’s technical workshops on the beneficial reuse of industrial byproducts, targeting states across the regions in an effort to bring together experts from all stakeholder groups to discuss the benefits of and barriers to building and maintaining highways constructed from reused and recycled materials and industrial byproducts. These candid exchanges are intended to facilitate the flow of information, thus creating an integrated decision-making process.

Our strategic goals listed below also include objectives for building partnerships and developing demonstration projects and outreach materials/resources

Conservation of non-renewable resources- Lime, gypsum, and aggregate are examples of mined materials which can be substituted with various recycled materials. New mines destroy green fields and impact wildlife habitat.

Reduced Energy Consumption and Greenhouse Gas Emissions- Virgin materials require energy intensive mining operations and often very energy intensive manufacturing and refinement which recycled or reused materials can help to reduce. For example, coal fly ash can be used to replace 20 percent or greater amounts of Portland cement in concrete. In addition, using local materials reduces transportation emissions, while in-place recycling can help conserve resources, costs and reduce the carbon footprint.

Reduced Land filling- Reusing industrial by-products reduces the need for additional landfill space. New landfill space can be costly and often involves lengthy permitting processes.

Reducing Repeated Cost- Recycled materials often have less transportation and refinement costs. Also, the costs associated with disposing of material is eliminated. Recycled materials often cost less than conventional/virgin materials.

Better Material Properties- Many reused and recycled materials perform better than the material they replace or bring additional performance benefits. Slag cement has a higher reflectivity than other cementitious materials. Lighter color concrete absorbs less heat, helping minimize the heat island effect. In another example, crushed glass has a higher frictional characteristic.

It is estimated that roadway and highway construction in the United States is currently consuming between 500 and 800 million metric tons of virgin crushed rock, gravel and sand each year as aggregate. The existing annual quantities of industrial by-product source materials, some 600 million metric tons, represents a way to significantly reduce the amount of virgin materials required for transportation infrastructure projects, natural resources, address energy and climate change issues and reduce the need for landfill space.

The materials matrix represented in Figure 1.0 prepared by the Industrial Resources Council, shows six major groups of by-product materials in the column headers, with the rows as potential applications.

LEGEND:Check marks indicate that a particular material-application combination has been used successfully, and that adequate data are available to prepare a description of the physical and chemical properties of the material and to describe the design requirements and performance records for one or more specific applications.

Omission of a particular material-application match in this matrix is not to be construed as a prohibition against its use; rather, omission indicates that either the material-application combination was inappropriate or that insufficient information was available to provide useful/accurate guidance.For additional information and user guidelines on 19 specific materials see UNH website: http://www.rmrc.unh.edu/tools/uguidelines/index.asp

Coal Combustion ProductsCoal combustion products (CCPs) are the byproducts generated from burning coal in coal-fired power plants. These byproducts include coal fly ash, bottom ash, boiler slag, and flue gas desulfurization gypsum. This information comes from the Coal Combustion Product Partnership, a cooperative effort between the U.S. Environmental Protection Agency, American Coal Ash Association, Utility Solid Waste Activities Group, US Department of Energy, and US Federal Highway Administration to help promote the beneficial use of Coal Combustion Products and the environmental benefits that result from their use.

Benefits of Using CCPsProper use of CCPs in building applications can yield environmental, economic, and product performance benefits. Using CCPs in an environmentally safe manner will save virgin resources, and reduce energy consumption and greenhouse gas emissions (GHG). In addition, it will help reduce the need for landfill space and new landfills. The use of CCPs also makes good economic sense since they are often less costly than the materials they replace.

Environmental BenefitsGreenhouse Gas Benefits: There are many ways in which the reuse of CCPs reduces the generation of GHG. For example, using existing CCP materials in place of virgin materials reduces energy intensive mining operations needed to generate virgin materials and the resulting emissions and fuel consumption that result in GHG. The primary GHG reductions associated with using coal ash come from its replacement of Portland cement in concrete. Portland cement is very energy intensive to manufacture. It takes the equivalent of 55 gallons of oil to produce a single ton of cement. The pozzolanic properties of coal fly ash make it a useful replacement for a portion of the Portland cement used in making concrete. Fly ash can typically replace between 15 to 30 percent of the cement in concrete with even higher percentages used for mass concrete placements. In addition, it makes the concrete stronger and more durable than concrete made with only Portland cement as the binder.

Benefits from Reducing the Landfilling of CCPs: Beneficially using CCPs instead of landfilling them also reduces the need for additional landfill space. The U.S. annually landfills over 83 million tons of CCPs. The landfill space required is the equivalent of placing 26,240 quarter acre home sites under 8 ft of CCPs. Landfill space in the U.S. is at a premium. Many energy facilities no longer have adequate storage space for CCPs. Beneficially using CCPs reduces the need to locate and develop new disposal facilities and any adverse environmental or health effects associated with them.

Benefits from Reducing the Need to Mine Virgin Materials: CCPs can be substituted for many virgin materials that would otherwise have to be mined. These include, lime to make concrete, natural gypsum for making wallboard and gravel for making roofing granules. Each of these materials would require mining virgin materials, potentially destroying green fields and wildlife habitat. It makes more sense to use existing materials that would otherwise be disposed of than to mine new ones. And, at the same time, waste and harm to the environment is reduced.

Performance and Economic BenefitsEach type of CCP has its particular performance benefits. For example, coal ash can be used to create superior products because of its inherent cementitious properties. Mixing fly ash with Portland cement mixtures can produce stronger and longer lasting buildings than concrete made with only Portland cement as the binder (glue). This not only reduces costs of maintaining buildings but provides the additional environmental benefit of reducing the need for new concrete to replace aging buildings–which consequently means a significant reduction in future energy consumption and GHG emissions. Boiler slag, which replaces sand in blasting grit, has the benefit of being free of silica which eliminates the potential health risk of silicosis.

SLAG CEMENTSlag cement is an essential cementitious material that will help define the future of concrete. The documents below are provided by the Slag Cement Association (SCA), the leading source of knowledge on blast furnace slag products.

FOUNDRY SANDSand casting is the most prevalent metal-casting technique used by the foundry industry. Because of its thermal conductivity, sand is used as a molding material, which forms the external shape of the cast part, and as cores, which form the internal void in products such as engine blocks. Foundry sand, the byproduct of the metal casting process, is a high quality silica sand with uniform physical characteristics. In modern foundry practice, sand is typically recycled and reused through many production cycles. Industry estimates are that approximately 100 million tons of sand are used in production annually. Of that, six to ten million are discarded annually and are available to be reused either in products or for construction activities. Two general types of binders are used in metal-casting-clay bonded sand (green sand) and chemically bonded sands (resin sands). Both types of sands are suitable for recycling and beneficial use though both have different physical and environmental characteristics. Green sand is composed of naturally occurring materials consisting of high quality silica sand, bentonite clay, carbonaceous additive (to improve the casting surface finish), and water. Green sand from iron, steel and aluminum foundries is the foundry sand type most commonly used in larger construction projects–structural fills, general fills, road and building bases, and embankments.

Benefits of Using Foundry Sand Foundry sands used for conventional construction materials results in positive environmental impacts, calculated in measurable energy savings, water reductions, and greenhouse gas and particulate emissions. Green sands also have engineering and economic benefits. Foundry sands have shown to perform well in structural fills and bases where they typically exhibit higher strengths than native soils.

Environmental Benefits Using foundry sands is environmentally beneficial because it reduces the amount of sand going to landfills and reduces water, fuel and energy consumed to mine new aggregate while at the same time reducing greenhouse gas emissions from mining and transportation equipment.

Performance and Economic Benefits Foundry sand is basically fine aggregate. It can be used in many of the same ways as natural or manufactured sands including applications such as embankments/site development fill, flowable fill, hot mix asphalt, road base, and Portland cement concrete. In geotechnical applications, foundry sand often demonstrates high durability. However, there is some variation in the foundry sand chemical composition from foundry to foundry and suppliers should understand and control foundry sand variability to provide customers with a consistent product. Foundry sand economics depends on availability and location of foundry sand and similar natural aggregates in the region. Generally, foundry sand is less expensive then select materials such as aggregate or crushed stone.

STEEL SLAGSteel slag is a byproduct from the conversion of iron to steel in the basic oxygen (major type), electric arc and open hearth* (minor type) steel making process consisting mainly of iron, lime and manganese. It is produced during the separation of the molten steel from impurities in steel-making furnaces. Processing of steel slags for steel recovery results in an angular rough surface texture, generally well-graded, material that is relatively free of metallics. Steel slag is then further processed into a coarse or fine aggregate material for use in wearing course hot mix asphalt, granular base, embankments, engineered fill, highway shoulders, and surface treatments. It requires proper selection, processing, aging and testing to ensure that it will perform in accordance with intended design specifications.

Benefits of Using Steel SlagProper processing and management of steel slag allows the slag to be recycled and used in various applications. The slag has unique physical and chemical properties that make it particularly well suited to a variety of uses in construction and civil engineering projects. As a substitute for natural aggregates, steel slag results in environmental, engineering and economic benefits especially where natural fine aggregate sources are limited.

Environmental Benefits Steel slag has a long history of environmentally safe application and positive environmental benefits. A human and ecological risk assessment for steel slag reinforces that steel slag conforms to the EPA’s stringent requirements and does not pose a threat to human or plant life. The use of slag as aggregate reduces the need for virgin materials and the energy use and emissions produced during the mining, processing and transportation of those materials.

Performance and Economic Benefits Steel furnace slag provides superior skid resistance, and high stability properties. In addition, steel slag provides good frictional properties, improved durability, hardness and bonding characteristics. However, steel slag aggregates generally exhibit a propensity to expand due to the presence of free lime and magnesium oxides that have not reacted with silicate structures and that can hydrate and expand in humid environments. Steel slag should be stockpiled outdoors for several months to allow potentially destructive hydration and its associated expansion to take place prior to use of the material in aggregate applications.

Roughly 300 million scrap tires are generated each year in the United States, approximately 1 tire per person in the country. Most of these tires are reused in various applications, though about 40 million tires still go to landfills or other land disposal options. There are also still about 180 million tires in stockpiles. When recycled, scrap tire material replaces some other material currently used in construction such as lightweight fill materials like expanded shale or polystyrene insulation blocks, drainage aggregate, or even soil or clean fill. Tire derived aggregate has very useful engineering properties that make these materials an excellent choice for construction applications. For road construction, tires can be cut into small pieces to produce tire derived aggregate (TDA). TDA is a lightweight aggregate with good drainage and insulation properties. TDA has been used successfully to support embankments and roads on weak or marshy soils. Recycled tires can also be used as ground rubber for hot mix asphalt.

Benefits of Recycled Rubber TDA has been used successfully to support embankments and roads on weak or marshy soils. There are approximately 75 tires worth of TDA in 1 cubic yard, so a large project can use a significant number of tires. Scrap tire recycling as either TDA or ground rubber has many environmental and performance benefits in addition to economic savings.

Environmental BenefitsLike any material, care must be taken to ensure the tires are not contaminated by debris that may be harmful. In general, reusing scrap tires has a number of positive environmental benefits. Reusing scrap tires conserves valuable landfill space, and reducing stockpiles decreases the risk of tire fires and the related adverse environmental impact. As TDA, it provides a high quality construction material that reduces the need for mining virgin aggregate and the associated use of water, fuel and reduces carbon dioxide emissions.

Performance and Economic BenefitsFor most projects, using tire shreds as a lightweight fill material is significantly cheaper than alternatives. Tire shreds are used as subgrade fill and embankments which include retaining forest roads, protecting coastal roads from erosion, enhancing the stability of steep slopes along highways, and reinforcing shoulder areas. Ground rubber can be used in hot mix asphalt to improve performance and reduce maintenance.

Reclaimed concrete aggregate (RCA) is a popular substitute for natural stone aggregates. RCA is obtained from the demolition of Portland cement concrete (PCC) structures such as PCC pavements, sidewalks, curbing, building slabs and runways. The concrete may be hauled to a central facility for stockpiling and processing, though on transportation projects the concrete is often crushed in place using a mobile plant. Processing generally involves crushing the concrete and screening it to remove soil and fine particles. Reinforcing steel is removed during processing by magnetic separators. The resulting RCA is composed of high quality mineral aggregates bonded to pieces of the hardened cement paste. RCA properties make it appropriate for use as aggregate in new PCC, granular fill and base course layers in pavements.

Environmental BenefitsIn general, properly using RCA has a number of positive environmental benefits. RCA provides a high quality construction material that reduces the need for mining virgin aggregate and the associated use of water, fuel and reduces carbon dioxide emissions. Reusing RCA saves valuable landfill space. The use of RCA in metropolitan areas reduces the need for transporting natural materials from distant quarries, and eliminates the need to transport the concrete to disposal sites, again saving fuel and reducing emissions.

Performance and Economic Benefits The RCA is a highly angular aggregate with good bearing strength and drainage properties, providing an excellent foundation for the hot mix asphalt layers. Some projects have shown that the RCA can actually gain strength with time due to self-cementation, and other projects found that the RCA helps stabilize wet, soft, underlying soils. In addition, mobile plants can be used to crush old PCC pavements at the site for immediate reuse.

Reference Links

Following are links to publications, documents, and resources pertaining to Reuse and Recycling

CONTACTS-EPA HeadquartersNicole Valimazar
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EPA Region III Offices of Solid WasteMary Hunt
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The Recycled Materials Resource Center at the University of New HampshireKevin Gardner
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University of Washington Craig Benson
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User Guidelines for Industrial Byproduct Materials in Pavement ConstructionThe User Guidelines have long been a key FHWA information resource for 20 different byproduct materials in road construction. The Guidelines were recently updated to include current information about the U.S. EPA’s Resource Conservation Challenge priority materials, coal ash, foundry sands and construction and demolition materials, along with current information about environmental considerations in the use of byproduct materials.http://www.recycledmaterials.org/tools/uguidelines/index.asp

EPA’s Comprehensive Procurement Guidelines (CPG) Contains information and links to construction and transportation products containing recycled content. Although the CPGs are primarily for federal procuring agencies, the information is useful to state and local governments and the private sector. You also can also view EPA's recommended recycled-content ranges and access a Supplier Database which includes manufacturers, vendors, and suppliers for each item. http://www.epa.gov/cpg/products.htm

Recycled Materials in European Highway Environments: Uses, Technologies, and PolicesFederal Highway Administration sponsored document that reports on innovative policies, programs, and techniques that promote the use of recycled materials in the highway environment.http://international.fhwa.dot.gov/pdfs/recycolor.pdf

FHWA POLICY AND TECHNICAL ADVISORIESFederal Highway Administration (FHWA) Recycled Materials Policy FHWA’s policy statement is designed to advance the use of recycled materials in highway applications. The policy outlines the importance of re-using materials previously used in constructing the Nation's highway system, and calls upon the FHWA and State transportation departments to explicitly consider recycling as early as possible in the development of every project.www.fhwa.dot.gov/legsregs/directives/policy/recmatmemo.htm

Technical Advisory T 5080.9. Use of Coal Ash in Embankments and Bases. U.S. Department of Transportation, Federal Highway Administration, May 1988The purpose of this technical advisory is to set forth guidance and recommendations relating to the use of coal ash in bases and embankments. This Technical Advisory covers the history of coal ash use in these applications along with discussions on environmental, design, and construction considerations.http://www.fhwa.dot.gov/legsregs/directives/techadvs/t508009.htm

Technical Advisory: Use of Recycled Concrete Pavement as Aggregate in Hydraulic-Cement Concrete PavementThis Technical Advisory issues information on state-of-the-practice and guidance for the use of recycled concrete pavement as aggregate in concrete used for pavements.http://www.fhwa.dot.gov/legsregs/directives/techadvs/t504037.htm

American Association of State Highway and Transportation Officials (AASHTO)The AASHTO Subcommittee on Materials focuses on developing specifications for materials used in the construction and maintenance of all transportation facilities including highways, bridges and structures, and standard methods of sampling and testing these materials; and serves as a conduit to exchange information on the performance of special products evaluated by AASHTO Member Departments. The Subcommittee on Materials also maintains and updates the Standard Specifications for Transportation and Methods of Sampling and Testing, and Provisional Standards Materials reference which contains 418 materials specifications and test methods commonly used in the construction of highway facilities.http://materials.transportation.org/default.aspx

Recycled Materials Resource Center (RMRC) Project 13/14: The Development and Preparation of Specifications for Using Recycled Materials in Highway ApplicationsRMRC’s project 13/14 focused on the development of specifications for recycled materials in highway construction. The RMRC is funded by the Federal Highway Administration and the U.S. Environmental Protection Agency.

The Energy & Environmental Research Center at the University of North Dakota conducted a state by state comparison of U.S. Department of Transportation specifications for using coal combustion products.www.undeerc.org/carrc/Assets/Vol1DOT.pdf

University of Wisconsin’s Beneficial Use Information Center (BUIC)The BUIC is a virtual center created by the Geotechnical/Geoenvironmental Group at the Department of Civil and Environmental Engineering at the University of Wisconsin-Madison to provide a location where designers and users can access information, including specifications, relevant to the beneficial reuse of foundry byproducts

Evaluation of Industrial Waste Evaluation Model (IWEM) For Non-Federal Users With Regard to Highway ApplicationsFunded by the U.S. EPA, the Recycled Materials Resource Center conducted work to evaluate whether IWEM can be used as a predictive tool to accurately determine whether leaching from materials will result in significant changes in groundwater concentrations when the materials are reused as a base or sub-base in a roadway. Click on the link and scroll down under “Key Resources.”Visit: Evaluation of IWEM For Non-Federal Users With Regard to Highway Applications (PDF)

Geo Engineering Report No. 05-22: Assessing Groundwater Impacts from Coal Combustion Products Used In Highways The Department of Civil and Environmental Engineering at the University of Wisconsin-Madison evaluated a computer application, called WiscLeach, that was developed to assess impacts to groundwater caused by leaching of trace elements from coal combustion products used in highway construction. This study was funded by the Wisconsin Department of Natural Resources Waste Reduction and Recycling Demonstration grant Program and Alliant Energy. Visit: Geo Engineering Report No. 05-22:

Geo Engineering Report No. 05-21: Metals Leaching from Highway Test Sections Constructed with Industrial ByproductsDescribes the results of a study by the Department of Civil and Environmental Engineering at the University of Wisconsin-Madison to assess metals leaching from industrial byproducts (foundry sand and foundry slag from a gray-iron foundry; and bottom ash and fly ash from a coal-fired power plant) used in highway construction. This study was funded by the Recycled Materials Research Center through the Wisconsin Department of Transportation, the Wisconsin Department of Natural resources Waste reduction and recycling Demonstration Grant Program, and Alliant Energy. Geo Engineering Report No. 05-21

Foundry Industry Starts Recycling Today (FIRST) Roadway Case StudiesThe FIRST website provides several case studies on the beneficial use applications for spent foundry sand under the “Technical Applications” tab. The initial case studies were developed for FIRST under a grant from U.S. EPA Region 5. Registered users of the foundryrecycling.org Web site can download these case studies. Registration is free.

Kukkia Circlet Environmentally Friendly System to Renovate Secondary RoadsA research and demonstration project in Finland on the use of boiler ash and wastewater residual solids from pulp and paper mills in improving unpaved roads.www.ramboll.fi/luopioinen/life/html/julkaisut_en.htm

EPA’s C2P2 Website: Benefits of using CCPs Using CCPs in an environmentally safe manner saves virgin resources, and reduces energy consumption and greenhouse gas emissions (GHG). In addition, it helps reduce the need for landfill space and new landfills. CCPs also makes good economic sense, they are often less costly than the materials they replace. This site gives an overview of these beenfits.http://www.epa.gov/epawaste/partnerships/c2p2/use/benefits.htm

Beneficial Reuse Model (BenReMod)BenReMod is a model that allows state and local regulators, end users, and the public to evaluate the benefits and disadvantages of using recycled materials in road construction. It is currently being developed by the University of Toledo in partnership with the American Coal Ash Association, Great Lakes Byproducts Management Association, and the Ohio Environmental Protection Agency.http://benremod.eng.utoledo.edu/BenReMod/

MID-ATLANTIC GREEN HIGHWAY PARTNERSHIPGreen Highways Partnership- Recycling and Reuse of Industrial Materials TeamInformation on recycling and reusing industrial materials in roadways, which is a component of the Mid-Atlantic Green Highways Partnership. http://www.greenhighways.org/reuse_Recycling.cfm